Lead Frame Burr Flattening for Resin Leakage Prevention
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Solution Overview
Problem
Resin leakage occurs during the resin-molding process of semiconductor devices due to surface burrs on the lead frame, leading to resin leakage portions on the tie bar and outer leads, which cause yield and reliability issues.
Innovation Solution
Applying a compressive pressure greater than the clamping pressure to the lead frame before resin-molding to flatten the burrs and create a dent portion, preventing resin leakage and ensuring a secure anchor for the lead frame within the resin package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead frame is pressed by the upper mold and lower mold during resin-molding, then the resin is prevented from leaking, but resin leakage portions are still formed on the surfaces of the tie bar and outer leads due to burrs on the lead frame surface
Solution Approach 1:
The patent applies a preliminary compressive pressure to the lead frame before resin-molding to flatten the burrs on the surface. This preliminary action removes the surface irregularities that would otherwise cause resin leakage, ensuring that the subsequent resin-molding process can proceed without forming resin leakage portions on the tie bar and outer leads.
Solution Approach 2:
The patent changes the physical state of the lead frame surface by applying compressive pressure, which flattens the burrs and improves surface flatness. This parameter change (from burr-containing surface to flattened surface) enables the resin to be properly contained during molding without leaking through the gaps created by surface irregularities.
2Reliability
If a compressive pressure is applied to flatten the burrs on the lead frame surface, then resin leakage is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines the burr-flattening process with the existing resin-molding process by applying compressive pressure through the same upper and lower molds used for molding. This merging of functions allows the lead frame surface to be prepared and the resin to be molded in a single integrated process, avoiding the need for separate burr-removal equipment or steps.
Solution Approach 2:
The resin-molding molds themselves serve the dual function of both applying compressive pressure to flatten burrs and subsequently molding the resin. The same upper and lower molds that will contain the resin during injection are used to apply the preliminary compressive pressure, making the existing equipment perform an additional preparatory function.
3Reliability
If the clamping pressure is increased to prevent resin leakage through gaps, then resin leakage is reduced, but the lead frame may deform or the bonding may be affected
Solution Approach 1:
The patent applies compressive pressure to flatten burrs before the resin-molding process begins. By removing the surface irregularities that create gaps beforehand, the subsequent resin-molding can proceed at normal clamping pressures without risking lead frame deformation or bonding damage, while still preventing resin leakage.
Solution Approach 2:
The preliminary compressive pressure acts as a cushioning measure that eliminates the root cause (burr-induced gaps) of potential resin leakage. By addressing the surface irregularities in advance, the system avoids the need for excessively high clamping pressures that could damage the lead frame or affect bonding integrity during the actual molding process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents resin leakage during the molding process and enhances the reliability of the semiconductor device by ensuring the lead frame is securely anchored, reducing the risk of resin flaking off and improving yield.
Implementation Method 1
applying a compressive pressure greater than the clamping pressure to the lead frame before resin-molding to flatten the burrs and create a dent portion
Data Source
AI summary
This invention is directed to provide a method of manufacturing a resin molded semiconductor device with high reliability by preventing a resin leakage portion from occurring due to burrs on a lead frame formed by punching. The method of manufacturing the resin molded semiconductor device according to the invention includes bonding a semiconductor die on an island in a lead frame, electrically connecting the semiconductor die with the lead frame, resin-molding the lead frame on which the semiconductor die is bonded, and applying prior to the resin-molding a compressive pressure that is higher than a clamping pressure applied in the resin-molding to a region of the lead frame being clamped by molds in the resin-molding of the lead frame.